Q & A

"What can I do to keep water out of my oil?"

Despite its reputation to the contrary, oil likes water, at least a certain
amount. Dry oil will move to absorb water from the air if there is any humidity
in the air. So, keeping water out of oil is a challenge.

Water enters the oil through fill ports, poor seals, broken heat exchangers
and from humidity in the air. Humidity is likely the biggest problem, particularly
in parts of the world where relative atmospheric humidity is high. In these
cases it is a good idea to purchase and install hygroscopic (desiccant) breathers
so that air entering the headspace will be stripped of moisture.

Other alternatives would be to condition the headspace and/or elevate the temperature
of the oil in the system to drive off water that has entered the reservoir.
A third option is to use filters/separators that evaporate, drive off or absorb
the water in a kidney-loop approach.

In some situations all of these approaches in combination may be warranted.

Today's Tip

Many synthetic lubricants offer a one benefit that mineral-
based lubricants typically do not. Energy savings due to the
lower frictional characteristics of certain synthetics can be
found to be as high as 5-10 percent. This is very significant
considering the approximate annualized cost of $25,000 in
electricity for a 150 hp (112 kW) compressor.
(Tip submitted by Roger Littlejohn, Citgo Lubricants. Thanks
Roger!)

Book Bits

From the newly revised book "Lubrication Fundamentals":

Drain intervals can vary considerably depending on the engine and service.
For example, a large diesel engine in central station use, with a relatively
large crankcase oil supply, may operate for thousands of hours between oil changes.
Such engines are usually in good adjustment, temperatures are moderate, and
the contamination rate is low in comparison to the volume of oil in the system.
On the other hand, a passenger car engine may require an oil change every few
thousand miles. Such engines are physically small with relatively small crankcase
capacity, and operate under conditions conducive to rapid oil contamination.
Not only are load factors often low, but these engines may be engaged mostly
in short runs and start- stop service, as well operating over wide ranges of
ambient temperature, all of which favor the accumulation of oil contaminants
and the risk of deposits.

The presence of an oil filter does not necessarily permit an extension of the
oil drain interval. Filters do not remove oil- soluble contaminants and water,
which are important factors in deposit formation. Regular filter changes are,
however, important in keeping the filter operable so that it can perform its
function of removing insoluble contaminants from the oil.